In recent years there has been growing interest in a variety of non-detergent based technologies for washing laundry and other soiled substrates. For example, a number of washing machines have been launched on the Japanese and Asian markets that make use of electrolysis, ultrasonic or cavitation techniques to promote the cleaning or disinfection of laundry. Typically, such machines include at least one wash cycle characterized as ‘detergent-free’ and which is designed for the washing of laundry that is relatively lightly soiled. As the washing machine manufacturers themselves make clear, however, the machines and systems currently on the market are of limited value for the washing of more heavily soiled or stained items where the use of a surfactant-based detergent product continues to be necessary to achieve acceptable cleaning performance. Accordingly, such machines are designed and marketed for so-called ‘hybrid’ use with non-detergent and detergent wash-cycles being selectable according to the severity of the laundering task.
In terms of overall resource utilization, the non-detergent based cleaning technologies may have the potential to save on detergent product usage in light soil situations, but such savings are offset to a lesser or greater extent by the operational need for higher water and energy utilization. Thus the resource equation is finely balanced.
It clearly would be desirable to enhance the efficacy of current washing machines and systems, including the newer ‘hybrid’ machines, so as to deliver improved washing performance across the full range of detergent usage levels. It would also be desirable to deliver performance improvements in the context of an overall efficient and sustainable utilization of resources—chemical, water and energy.
It is an object of the present invention to provide methods and systems applicable in the field of domestic or institutional appliances such as laundry washing machines, automatic dishwashing machines, etc and which enable improved cleaning of a soiled substrate or substrates across the range of detergent usage levels. It is a further object of the invention to provide washing methods and systems enabling more efficient usage of water, energy and detergent product resources.